Electromagnetically operated switch



Nov. 10, 1931.

P. TROMBETTA ELECTROMAGNETICALLY OPERATED SWITCH Filed July 18, 1927 Joy 2 Sheets$heet l I m/enbor I an? i lo Tromb ett a,

H is AUGOYYW 6y.

- PANI'ILO Patented Nov. 10, 1931 QUNITED STATES PATENT OFFICE momma. or scnmn'c'rmy, NEw' YORK, ASSIGNOR 'ro GENERAL ELEC- r310 oourm, a conromrron' or NEW YORK ELEC'I'BDMAGNETIGALLY OPERATED SWITCH Application filed July 18,

on the electromagnet, as well as an improved mechanism for operatively connecting the movable switch element and the movable magnetic member of the electro'magnet.

The improvements of the present inven? tion are particularly advantageous where the tracted position by roviding an auxiliary I switch is used to control the energizing circuit of the electromagnet during the operation thereof. For example, it is common pactice in direct current. service to reduce vthe energization of an electromagnet upon operation of the magnetic member to the atswitch operableby t e magnetic member to insert a resistance in the energizing clrcuit of the electromagnet. The present invention provides an im roved switch that readily may be arrange to either close its contacts or open its contactsupon operation of the electromagnet and the improved operating mechanism of the switch requires on y a very slight final movement of the magnetic member of the electroma et for effecting operation of the switch. oreover, the operating mechanism is such that the switch actually may be operated afterthe completion of the slight final movement of the magnetic member of the electromagnet. In. addition, both tion will appear rom the following description of the accompanying drawings in which the switch and the operating mechanism may readily'be mounted directly on the frame of the electromagnet thereby ermitting a simplified and compact mounting of the electromagnet and the control switch mechanism therefor.

Other advanta eous features of the inven- Fig. 1 is a plan view of an electromagnet provided with the improved form f controlling switch mechamsm and operating mechanism ofthe present invention, the switch being of the normally closed type; Fig. 2 is a sectional view of the electromagnet andswitohmechanism of Fig. 1 show- 1927. Serial No. 206,466.

ing more clearly the details of construction- Fig. 3 is a top view of the electromagnet and the normally closed switch of Fig. 1; Figs. 4 and 5 are circuit diagrams showing schematically the normally closed control switch arranged to control the energization of the operating windings of the electromagnet uponoperation of the electromagnet; Fig. 6 1s a plan view of the switch arranged to be normally in the circuit opening position and operable to the circuit closing position upon operation of the electromagnet; Fig. 7 1s a sectional view of the electromagnet of the normally open switch of Fig. 6; Fig. 8 is a top view of the electromagnet and normally open switch; and'Fig. 9 is a circuit diagram showing the connections used for enabling the normally open switch to connect'the portions of the operating windings of the electromagnet in parallel circuit after operation thereof.

Referring to Fig. 1, the electroma-gnet lo is shown of the improved form described and claimed in my copendjng application Serial N 0. 189,878, filed May 9, 1927, which became Patent N 0. 1,696,615 on December 25, 1928,

with which the improved form of switch mechanism and operating mechanism of the present invention is particularly adapted for use. It will be understood, however, that the improvements of the present invention may be applied to other suitable forms of electromagnet. Briefly, the electromagnet 10 com;

prises a laminated frame 11 having the laminations held together by the angle supporting pieces 12. The frame 11 is provided with* an opening 13 on one side thereof through which the movable magnetic member or plunger'l l operates upon energization of the ener izing windings 15. The plunger 14 has an en arged head 16 providing the rojecting, shoulders 17 on either side thereo for magnetically sealing with the sides of the frame 11 adjacent the opening 13 when the plunger is operated to the attracted position.

The switclrmech'anism 18 is arranged to be operated by the final movement of the plunger 14 to the attracted position through the agency bf the operating member 19. The

switch mechanism 18 in the preferred form shown comprisesthe two sets of stationa spaced apart contact elements 20 and-21 wit which the movable bridging contact elements 22 and 23 respectively cooperate. The stationary spaced a art contacts 20 and 21 are mounted upon t e base'24 formed of insulating material, such as bakelite or the like, by means of screws 25 and 26.. The base 24 is secured to a yoke member 27 with the in- .sulating sheet 28 interposed therebetween b means of the bolts 29. The whole switc mechanism 18 is mounted directly upon the frame of the electromagnet 10 by' means of the bolts 30 which pass through suitable holes formed in the electromagnet frame 11 and clamp the oke 27 securelythereto.

As may he 'moreclearly seen in Fig. 3, the movable contact members 22 and 23 brldge between the stationary contacts and 21 al- 20 though a single stationary contact with a cooperatin movable contact may be employed if desire The movable contacts 22 and 23 are yieldingly mounted upon the movable contact arm 31 by means of the square post 32 and the springs 33 which are interposed between the contacts and the washer 34 held upon the end of the post 32 by the bolts 35. The two movable contacts 22 and 23 are suitable for controlling the same circuit one serving as an arcing contact and the other as the main current carrying contact or the contacts may control separate circuits if desired. -1

' The movable contact arm 31 is arrangedto be mounted in two different cooperating rela- 35 tions with the stationary contacts 20 and 21 one relation resulting in the. normally close switch shown in Fig. 1 and the other relation resulting in the normally open switch shown in Fi 5. In the arrangement of Fig. 1 the mova 1e contact arm 31 is pivotally mounted upon the pin 36 which is sup orted at Its ends by the'spaced apart arms 3 which preferably are formed on the base 24. A double wound biasing spring 38 having its outer ends 38A seated in the recesses 39 formed in the base 24 and the inner looped end'38B engaging witha downturned tongue 40 formed on the contact arm 31 serves to bias the contact arm tocarry the bridging contacts 22 and 23 into engagement with the respective contacts cooperating therewith.

The operating-member 19 for the switch mechanism is formed of a lever 41 referablyf of channel shape as shown in ig. 3

having a strip 42 secured thereto as by rivetingwith one end of the strip bent up to formt ap'rojecting. substantially knife-edge sup,-

' ort for-pivotally mounting the lever arm 41 1n the open slot 43 which is formed in the p side .of electromagnet frame 11 ad'acent'the opening 13. The open slot 43 is ormed by providmg a notch in each of the lammatrons comprising the frame 11 which, when superimposed, forms an open slot. across the out-' side of the frame. The ends of the slots are wisedirection about the pivot pin 36. In this way the switch contacts 22 and 23 are electromagnet as follows: Upon suitable closed by the angle supports 12, thus pre venting lateral 'splacement of the lever arm 41. The other end of the strip 42 is bent over to form a stop 44 engaging with the adjacent side of the electromagnet frame 11 as indicated in Fig. 2. The biasing spring 45 is connected between the stop 44' and the tongue 27' extending from the yoke member 27. bpring 45 serves to hold the operating member 19 in ivotal engagement with the electromagnet rame 11 and also biases the member 19 to a position in which the stop 44 engages with the side of the electromagnet frame with the end of the operating member 19 on the opposite-side of'the pivotal support in spaced relation between the side of the frame 11 and the head of the plunger 14. This end of the operating member 19 thus is in the path of movement of the ofi'set projectmg shoulder 17 so as to be engaged thereby upon the final movement of the plunger 14 to the attracted position. The other end of the operating member 19 isyieldingly connected with the switch operating arm 31 by means of the spring 46. One end of the spring 46 is hooked directly into a hole formed in the end of the operating member 19 and the other end of the spring is hooked into an e e member 47 which is detachably secure to the switch arm 31 by means of the' removable pin 48. The arrangement of the spr ngs,45 and 46 is such that when the spr1ng 45 maintains the stop 44 on the pivoted operating member 19 in engagement with the magnet rame as shown in Figs. 1 and 2, there is relatively little strain or tension in the spring 46, the latter serving simply as a yieldlng connection between the operating member 41 and the swtich mechanism. Moreover, with the double wound bias spring 38 for the switch mechanism having its outer ends 38A anchored in the recess 39 formed in' the base.24 and itsinner looped end 38B engaging with the downturned tongue 40 on the contact arm'31 as shown in 'I igS. 1, 2 and 3, the ends 38A and 38B of the spring are. maintained under a tension to move togather and thereby exert a force tending to rotatethe contact arm 31 in a counter-clockbiased to the circuit closed position.

The. operation of the normally closed switch as shown in Figs. 1, 2 and 3 by the 100 energization of the operating windings of the electromagnet the plunger 14 is moved to the attracted position in which the enlarged head 16 of the plunger brid es across the opening 13 formed in the side of the electromagnet frame 11. Just before the plunger 14 enga es with the frame 11, the offset shoulder 1 is arranged to strike the end of the operating member 19 which pivots upon its protecting support in the slot 43 and thereby sets up a strain in the resilient connecting spring 46 tending to eifect operation of the switch arm 31 to the circuit opening position. 5 Due to the high speed at which the projection 17 strikes the operating member, 19, the inherent inertia of the switch arm 31 carrying the bridging contacts 22 and 23, and the resilient connection between the operating member and the switch arm, the actual movement of the bridging contacts 22 and 23 to the circuit opening position may occur after the completion of the movement of the plunger 14 to the attracted position. The resilient connection between the operating member and the switch arm also insures that the shock produced upon the impact of the head of the plunger'let with the operating member 19 is not transmitted directly to the 20 switch arm 31. The separate mounting of the operating member 19 directly upon the electromagnet frame 11 insures that the end of the operating arm is in the proper spaced relation inthe path of the head of the plunger 14 'to produce operation with a minimum final movement of the plunger. Tn fact the final movement required for operation of the operating arm 19 may be a very small fraction of an inch whereas a much larger travel of the plunger would be required with the operating member 19 mounted in the usual manner.

It will be understood that the electromagnet is mounted so that upon deenergization of the operating winding the plunger 14 falls from the attracted position and thereby disengages the offset shoulder 17 from the operating member 19. The biasing spring serves to return the operating member 19 into 40 the position shown in the drawings, thereby relieving the strain in the connecting spring 46. This permits the biasing spring 38 to return the switch arm 31 to its normal on 5 cuit closing position as indicated in the drawin s.

llVhile the improved form of switch mech' anism shown may be employed to control any circuit or circuits desired, it is particularly adapted to control the energizing circuit of the electromagnet itself. Thus, as

diagrammatically shown in Fig. 4, the normally closed switch mechanism 18 may be emplo ed to insert a resistance R in the circuit o the operating windings 15 of the electromagnet when the plunger 14 is operated to the attracted position In this way the energy input to the electromagnet may be materially reduced after the plunger 14 has completed its working stroke and has substantially closed the magnetic circuit of the control arrangement of Fig. 4, if desired. As

shown in Fig.3, the normally closed switch mechanism 18 is connected to normally short circuit a portion of the operating winding 15 of the electromagnet. The short circuited portion preferably is of relatively high resistance, while the remaining portion of the operating windings is arranged to supply the ampere turns required to effect operation of the movable magnetic member to the attracted position. "hereupon the switch mechanism 18 operates to insert the high resistance portion of the operating windings in series circuit with the operating portion. As

a result the operating cnrrent of the electromagnet is materially reduced when the movable magnetic member is in the attracted position with a corresponding reduction in th watts input tothe electromagnet.

To convert the switch. mechanism with which the electromagnet is provided from the normally closed type illustrated in Figs. 1 1, 2, and 3 to the normally open type illustrated in Figs. 6. 7, and 8, it is only necessary to shift the pivot supporting pin for the switch arm 31 and the supporting pin -for the eye member 47 and rearrange the engagement of the biasing spring 38 with the base 24 and the switch arm 31. Thus, the

pivot pin 36 is shifted to the holes in the switch arm previously occupied by the pin 48 and to the correspo-ndin holes 49, which are formed in the arms 3 of the base 24 and the supporting pin 48 for the eye member 47 is shifted to the holes in the switch arm 31 formerly occupied by the pivot pin the shoulder on the switch arm 31 as indicated in Figs. 5 and 7. In this modified arrangement? the biasing spring 38 is assembled with the ends 38A and 38B of the spring under compression sons to tend to move apart and thereby functions to bias the switch gear-s31 to carry the bridging contacts 22 ,and 23 out of engagement with the stationary contact elements 20 and 21. The spring 45 functions to hold the operating member 19 in its pivotalsupport in the slot 43 in the electromagnet frame 11 with the end of the operating member in the path of the shoulder 17 on plunger 14 in the same manner as previously described. The spring 46 extending between the end of the operating arm 19 and the eye member 47 also serves to provide a resilient connection between the operating member 19 and the switch mechanism to absorb shock and permit operation of the switch arm to follow the completion of the stroke of-the plunger as set forth above. v

The operation of the switch mechanism in its modified form is as follows: The engagement of the offset shoulder 17 and the head of the plunger 14 upon the final movement of the plunger to the attracted position sets up a strain in the connecting spring 46 which operates the switch arm 31 to carry the bridging contacts 22 and 23 into circuit closing engagement with the cooperating stationary contact elements 20 and 21. With the electromagnet mounted to permit the plunger the attracted position. This connection arrangement is of particular advantage where the electromagnet is operated in series with other devices such as motors in a direct current circuit for controlling friction brakes, switches or the like, as it permits the energizing ampere turns of the electromagnet to be decreased when the plunger 14 is in the attracted position.

With the connections as shown in Fig. 9, the lower portion of the divided operating winding 15 is energized initially and serves to supply the attractive force necessary to effect operation of the plunger 14 to the attracted position. Preferably the lower portion of the operating windings is formed of a large number of turns and consequently has a relativelyhigh resistance. Vith the plunger 14 in the attracted position. a very much reduced attractive force is suflicient to hold the plunger in the attracted position. Thus the switch mechanism 18 is arranged to connect the upper portion of the operating windings in parallel circuit with the lower portion. With the upper portion of the operating windings of relatively few turns and relatively low resistance, the major portion of the current in the series circuit will flow through the upper portion while the lower portion of the operating windings will be energized in accordance with the voltage drop across the upper portion. In this way, the effective ampere turns of the operating windings may be materially reduced with a corresponding reduction in the watts input.

While I have illustrated and described a preferred form of switch mechanism and operating mechanism, embodying the improvements of the present invention, it will be understood that changes and modifications may be made therein without departing from the spirit and scope of the invention.

WhatI claim as new and desire to secure by Letters Patent of the United States is:

1. The combination of an electro-magnet having a magnetic member movable to the attracted pos1tion upon energization of the electromagnet,contacts operated by the said movement of said magnetic member, adjustable biasin means whereby said contacts may be ld111$t8d at will so as to be either normally open or normally closed, and cooperating adjustable connections between the magnetic member and contacts whereby said contacts may be either closed or opened upon movement of the magnetic member to the' at tracted positiondepending upon the adjust ment of said connections.

' 2. The combination of an electroma net having relatively movable magnetic mem ers with an air gap therebetween arranged substantially to be closed upon energization of the electromagnet, and switch mechanism associated with the electromagnet and having an operating member mounted on one of the magnetic member and disposed in the air gap therebetween closely adjacent said one magnetic member to be operated during final movement of the magnetic members to close said air gap.

The combination of an electromagnet having a magnetic structure including a frame and a cooperating magnetic plunger provided with an enlarged head for magnetically sealing with the frame when operated into the attracted position, and a. switch mechanism for controlling the electromagnet mounted on the frame and having an operating member separately mounted on the frame and disposed in the path of movement of the said enlarged head to be operated thereby uponthe final movement of the magnetic plunger into the attracted position.

4. The combination of an electromagnet having a. magnetic frame and a cooperating magnetic plunger provided with an enlarged -head magnetically sealing therewith, and

a switch mechanism mounted on the frame of the electromagnet and having a. separately mounted operating member resiliently connected with'the switch mechanism and-extending intothe path of movement of said enlarged head to be operated thereby upon the final movement of the magnetic plunger to the attracted position.

5. The combination of an electromagnet having a magnetic structure including a frame provided with an opening therein and a movable plunger operable in said opening and provided with an enlarged head magnetically sealing with the sides of the frame adjacent said opening when the plunger is in the attracted position, a switch mechanism for controlling the electromagnet removably mounted on the frame thereof and having means for biasing the switch mechanism to a predetermined circuit controllin position, an operating member having a ife-edge mounting on the frame adjacent said opening with the end of the operating member ex tending in the path of movement of said en= larged head to be o rated thereby upon the final movement of t e plunger to the attracted position, and a yielding connection between the operating member and the switch member to permit operation of the switch mechanism against its bias to follow operation of the said operating member.

6. The combination of an electromagnet having a' magnetic frame provided with an air gap therein and a slot inthe frame adjacent said air gap, a magnetic plunger movable in said air gap to the attracted-position and having an enlarged head for magnetically sealing with the sides of the frame adjacent said air gap, switch mechanism mounted on the frame, and an operating member for the switch mechanism provided with a knife-edged projection for pivotally mounting the operating member in the said slot with a portion of the operating member extending into the path of movement of said enlarged head to be engaged thereby upon operation of the magnetic plunger to the attracted position.

7. The combination of an electromagne t having a magnetic frame provided with an I opening in one side thereof and provided with a slot in the frame adjacent said opening, movable magnetic plunger operable through said opening and having lateral projections cooperating with the sides of the frame ad-= jacent said opening, switch mechanism mounted on the frame, an operatin member therefor provided with a projection inter= mediate its ends for pivotally mounting the operating member in saidslot in the frame independently of the mounting of the switch mechanism with one end of the operating member in'the path of movement of one out said lateral project-ions of the plunger, and

a resilient connection between the other end of the operating member and the switch meme her for permitting move'ment of the switch opening in the frame and havinglateral pro= ections magnetically cooperating with the sides of the frame adj ent the opening when the member is in the attracted position, switch mechanism removably secured to another side of the frame of the electromagnet, an operat ing member providcd' 'with, a projection intions of the movable magnetic member to he termediate its ends :ior pivotally mounting the member in the said open slot in the frame with one end of the member extending into the path of movement of one of the projec= operated thereby upon the final movement oi the magnetic member into the attracted posi-= tion, and a spring connected between the other end of the operating member and the switch mechanism and forming a yielding operating connection therebetween permit ting movement of the switch mechanism to follow movement of the operating member upon operation of the movable magnetic member to the attracted position.

9. An electromagnet having controlling switch mechanism therefor provided with in terchangeable pivotal supports and operating connections for permitting operation to either the circuit opening position or the circuit closing position upon operation of the electro magnet.

10, An electromagnet having a switch mechanism associated therewith for varying the energizing circuit of the electromagnet during operation thereof, said switch mecha= nism having a movable circuit controlling member and operative, connections between the movable circuit controlling member and the movable magnetic member of the electromagnet arranged to be assembled in two different relations, one for ed'ecting closure of a circuit upon energization of the electromagnet and the other for edecting the opening of a circuit upon energiaation of the electro :urmsznet 11. The combination of an electromagnet having a movable magnetic member, switch mechanism mounted on the electromaanet and having a movable circuit controlling member connected to be operated upon the final movement of the movable magnetic member to the attracted position. the said connections being adiustable to efiect move ment of the movable circuit controlling memnor to either the circuit opening or the circurt closing position upon operation of the movable magnetic member to the attracted position,

12. The combination of an electromagnet having a movable magnetic member, a switch mechanism including aiixed switch element mounted on the electromagnet, a cooperating movable switch element adapted for pivot-- ally mounting on either of two different axes and having adjustable biasing means for establishing correspondingly different circuit controlling relations with the fixed switch member, an operating member for the switch separately mounted on the electromagnet to be operated by the movable magnetic member thereof, and a spring adjustably connected movable switchelement for operating the between the said operating member and the same in each of said circuit controlling relations. I

13. The combination of an electromagnet having a movable magnetic member, a switch for varying the energizing circuit of the electromagnet during operation thereof, said switch comprising an insulating base removably mounted on the electromagnet and having a fixed switch element secured thereto, a cooperating movable switch element, means for mounting said movable switch element on either oftwo diflerent axes to establish corre spondingly different circuit controlling relations with said fixed switch element, one forming a normally closed switch and the other forming a normally open switch, an operating member for the switch separately mounted upon the electromagnet and extending into the path of movement of said movable magnetic member to be operated thereby. upon final movement thereof to the attracted position, and a spring for operatively connecting the operating member with the movable switch member in each of said circuit controlling relations.

14. The combination of an electromagnet having a laminated magnetic frame of rectangular shape provided with an opening in one side and having a notch formed in each laminationto provide a groove in the side of the frame adjacent said opening, a pair of angle supports secured on the opposite sides of said one side of the frame to bridge said opening and close the ends of said slot, a movable plunger operable through said opening lbetween said supports and having projections for magnetically cooperating with the sides of the frame adjacent the opening when the plunger is in the attracted position, switch mechanism removably mounted on another side of the frame of the electromagnet adjacent the side having said groove therein, an operating member for the switch mechanism having a projection for pivotally mounting the operating member in said groove with one end of the operating member isposed in spaced relation between the side of the frame and one of the lateral projec- .tions of said plunger to be engaged by said projection upon the final movement of the plunger to the attracted position, a spring resiliently connecting the other end of the operating member with the' switch mechanism, and a stop on the operating member engaging with said other side of the frame for maintaining the operating member in\a predetermined spaced relation with the frame.

In witness whereof, I have hereunto set my hand this 15th day of July, 1927.

PANFILO TROMBETTA. 

